mm/vmstat.c

   1 /*
   2  *  linux/mm/vmstat.c
   3  *
   4  *  Manages VM statistics
   5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   6  *
   7  *  zoned VM statistics
   8  *  Copyright (C) 2006 Silicon Graphics, Inc.,
   9  *              Christoph Lameter <christoph@lameter.com>
  10  */
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/err.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/cpu.h>
  17 #include <linux/vmstat.h>
  18 #include <linux/sched.h>
  19 #include <linux/math64.h>
  20 #include <linux/writeback.h>
  21 #include <linux/compaction.h>
  22
  23 #ifdef CONFIG_VM_EVENT_COUNTERS
  24 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
  25 EXPORT_PER_CPU_SYMBOL(vm_event_states);
  26
  27 static void sum_vm_events(unsigned long *ret)
  28 {
  29         int cpu;
  30         int i;
  31
  32         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
  33
  34         for_each_online_cpu(cpu) {
  35                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
  36
  37                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
  38                         ret[i] += this->event[i];
  39         }
  40 }
  41
  42 /*
  43  * Accumulate the vm event counters across all CPUs.
  44  * The result is unavoidably approximate - it can change
  45  * during and after execution of this function.
  46 */
  47 void all_vm_events(unsigned long *ret)
  48 {
  49         get_online_cpus();
  50         sum_vm_events(ret);
  51         put_online_cpus();
  52 }
  53 EXPORT_SYMBOL_GPL(all_vm_events);
  54
  55 #ifdef CONFIG_HOTPLUG
  56 /*
  57  * Fold the foreign cpu events into our own.
  58  *
  59  * This is adding to the events on one processor
  60  * but keeps the global counts constant.
  61  */
  62 void vm_events_fold_cpu(int cpu)
  63 {
  64         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
  65         int i;
  66
  67         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
  68                 count_vm_events(i, fold_state->event[i]);
  69                 fold_state->event[i] = 0;
  70         }
  71 }
  72 #endif /* CONFIG_HOTPLUG */
  73
  74 #endif /* CONFIG_VM_EVENT_COUNTERS */
  75
  76 /*
  77  * Manage combined zone based / global counters
  78  *
  79  * vm_stat contains the global counters
  80  */
  81 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
  82 EXPORT_SYMBOL(vm_stat);
  83
  84 #ifdef CONFIG_SMP
  85
  86 int calculate_pressure_threshold(struct zone *zone)
  87 {
  88         int threshold;
  89         int watermark_distance;
  90
  91         /*
  92          * As vmstats are not up to date, there is drift between the estimated
  93          * and real values. For high thresholds and a high number of CPUs, it
  94          * is possible for the min watermark to be breached while the estimated
  95          * value looks fine. The pressure threshold is a reduced value such
  96          * that even the maximum amount of drift will not accidentally breach
  97          * the min watermark
  98          */
  99         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
 100         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
 101
 102         /*
 103          * Maximum threshold is 125
 104          */
 105         threshold = min(125, threshold);
 106
 107         return threshold;
 108 }
 109
 110 int calculate_normal_threshold(struct zone *zone)
 111 {
 112         int threshold;
 113         int mem;        /* memory in 128 MB units */
 114
 115         /*
 116          * The threshold scales with the number of processors and the amount
 117          * of memory per zone. More memory means that we can defer updates for
 118          * longer, more processors could lead to more contention.
 119          * fls() is used to have a cheap way of logarithmic scaling.
 120          *
 121          * Some sample thresholds:
 122          *
 123          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 124          * ------------------------------------------------------------------
 125          * 8            1               1       0.9-1 GB        4
 126          * 16           2               2       0.9-1 GB        4
 127          * 20           2               2       1-2 GB          5
 128          * 24           2               2       2-4 GB          6
 129          * 28           2               2       4-8 GB          7
 130          * 32           2               2       8-16 GB         8
 131          * 4            2               2       <128M           1
 132          * 30           4               3       2-4 GB          5
 133          * 48           4               3       8-16 GB         8
 134          * 32           8               4       1-2 GB          4
 135          * 32           8               4       0.9-1GB         4
 136          * 10           16              5       <128M           1
 137          * 40           16              5       900M            4
 138          * 70           64              7       2-4 GB          5
 139          * 84           64              7       4-8 GB          6
 140          * 108          512             9       4-8 GB          6
 141          * 125          1024            10      8-16 GB         8
 142          * 125          1024            10      16-32 GB        9
 143          */
 144
 145         mem = zone->present_pages >> (27 - PAGE_SHIFT);
 146
 147         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 148
 149         /*
 150          * Maximum threshold is 125
 151          */
 152         threshold = min(125, threshold);
 153
 154         return threshold;
 155 }
 156
 157 /*
 158  * Refresh the thresholds for each zone.
 159  */
 160 void refresh_zone_stat_thresholds(void)
 161 {
 162         struct zone *zone;
 163         int cpu;
 164         int threshold;
 165
 166         for_each_populated_zone(zone) {
 167                 unsigned long max_drift, tolerate_drift;
 168
 169                 threshold = calculate_normal_threshold(zone);
 170
 171                 for_each_online_cpu(cpu)
 172                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 173                                                         = threshold;
 174
 175                 /*
 176                  * Only set percpu_drift_mark if there is a danger that
 177                  * NR_FREE_PAGES reports the low watermark is ok when in fact
 178                  * the min watermark could be breached by an allocation
 179                  */
 180                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 181                 max_drift = num_online_cpus() * threshold;
 182                 if (max_drift > tolerate_drift)
 183                         zone->percpu_drift_mark = high_wmark_pages(zone) +
 184                                         max_drift;
 185         }
 186 }
 187
 188 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
 189                                 int (*calculate_pressure)(struct zone *))
 190 {
 191         struct zone *zone;
 192         int cpu;
 193         int threshold;
 194         int i;
 195
 196         for (i = 0; i < pgdat->nr_zones; i++) {
 197                 zone = &pgdat->node_zones[i];
 198                 if (!zone->percpu_drift_mark)
 199                         continue;
 200
 201                 threshold = (*calculate_pressure)(zone);
 202                 for_each_possible_cpu(cpu)
 203                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 204                                                         = threshold;
 205         }
 206 }
 207
 208 /*
 209  * For use when we know that interrupts are disabled.
 210  */
 211 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 212                                 int delta)
 213 {
 214         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 215         s8 __percpu *p = pcp->vm_stat_diff + item;
 216         long x;
 217         long t;
 218
 219         x = delta + __this_cpu_read(*p);
 220
 221         t = __this_cpu_read(pcp->stat_threshold);
 222
 223         if (unlikely(x > t || x < -t)) {
 224                 zone_page_state_add(x, zone, item);
 225                 x = 0;
 226         }
 227         __this_cpu_write(*p, x);
 228 }
 229 EXPORT_SYMBOL(__mod_zone_page_state);
 230
 231 /*
 232  * Optimized increment and decrement functions.
 233  *
 234  * These are only for a single page and therefore can take a struct page *
 235  * argument instead of struct zone *. This allows the inclusion of the code
 236  * generated for page_zone(page) into the optimized functions.
 237  *
 238  * No overflow check is necessary and therefore the differential can be
 239  * incremented or decremented in place which may allow the compilers to
 240  * generate better code.
 241  * The increment or decrement is known and therefore one boundary check can
 242  * be omitted.
 243  *
 244  * NOTE: These functions are very performance sensitive. Change only
 245  * with care.
 246  *
 247  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 248  * However, the code must first determine the differential location in a zone
 249  * based on the processor number and then inc/dec the counter. There is no
 250  * guarantee without disabling preemption that the processor will not change
 251  * in between and therefore the atomicity vs. interrupt cannot be exploited
 252  * in a useful way here.
 253  */
 254 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 255 {
 256         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 257         s8 __percpu *p = pcp->vm_stat_diff + item;
 258         s8 v, t;
 259
 260         v = __this_cpu_inc_return(*p);
 261         t = __this_cpu_read(pcp->stat_threshold);
 262         if (unlikely(v > t)) {
 263                 s8 overstep = t >> 1;
 264
 265                 zone_page_state_add(v + overstep, zone, item);
 266                 __this_cpu_write(*p, -overstep);
 267         }
 268 }
 269
 270 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 271 {
 272         __inc_zone_state(page_zone(page), item);
 273 }
 274 EXPORT_SYMBOL(__inc_zone_page_state);
 275
 276 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 277 {
 278         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 279         s8 __percpu *p = pcp->vm_stat_diff + item;
 280         s8 v, t;
 281
 282         v = __this_cpu_dec_return(*p);
 283         t = __this_cpu_read(pcp->stat_threshold);
 284         if (unlikely(v < - t)) {
 285                 s8 overstep = t >> 1;
 286
 287                 zone_page_state_add(v - overstep, zone, item);
 288                 __this_cpu_write(*p, overstep);
 289         }
 290 }
 291
 292 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 293 {
 294         __dec_zone_state(page_zone(page), item);
 295 }
 296 EXPORT_SYMBOL(__dec_zone_page_state);
 297
 298 #ifdef CONFIG_HAVE_CMPXCHG_LOCAL
 299 /*
 300  * If we have cmpxchg_local support then we do not need to incur the overhead
 301  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 302  *
 303  * mod_state() modifies the zone counter state through atomic per cpu
 304  * operations.
 305  *
 306  * Overstep mode specifies how overstep should handled:
 307  *     0       No overstepping
 308  *     1       Overstepping half of threshold
 309  *     -1      Overstepping minus half of threshold
 310 */
 311 static inline void mod_state(struct zone *zone,
 312        enum zone_stat_item item, int delta, int overstep_mode)
 313 {
 314         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 315         s8 __percpu *p = pcp->vm_stat_diff + item;
 316         long o, n, t, z;
 317
 318         do {
 319                 z = 0;  /* overflow to zone counters */
 320
 321                 /*
 322                  * The fetching of the stat_threshold is racy. We may apply
 323                  * a counter threshold to the wrong the cpu if we get
 324                  * rescheduled while executing here. However, the next
 325                  * counter update will apply the threshold again and
 326                  * therefore bring the counter under the threshold again.
 327                  *
 328                  * Most of the time the thresholds are the same anyways
 329                  * for all cpus in a zone.
 330                  */
 331                 t = this_cpu_read(pcp->stat_threshold);
 332
 333                 o = this_cpu_read(*p);
 334                 n = delta + o;
 335
 336                 if (n > t || n < -t) {
 337                         int os = overstep_mode * (t >> 1) ;
 338
 339                         /* Overflow must be added to zone counters */
 340                         z = n + os;
 341                         n = -os;
 342                 }
 343         } while (this_cpu_cmpxchg(*p, o, n) != o);
 344
 345         if (z)
 346                 zone_page_state_add(z, zone, item);
 347 }
 348
 349 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 350                                         int delta)
 351 {
 352         mod_state(zone, item, delta, 0);
 353 }
 354 EXPORT_SYMBOL(mod_zone_page_state);
 355
 356 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 357 {
 358         mod_state(zone, item, 1, 1);
 359 }
 360
 361 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 362 {
 363         mod_state(page_zone(page), item, 1, 1);
 364 }
 365 EXPORT_SYMBOL(inc_zone_page_state);
 366
 367 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 368 {
 369         mod_state(page_zone(page), item, -1, -1);
 370 }
 371 EXPORT_SYMBOL(dec_zone_page_state);
 372 #else
 373 /*
 374  * Use interrupt disable to serialize counter updates
 375  */
 376 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 377                                         int delta)
 378 {
 379         unsigned long flags;
 380
 381         local_irq_save(flags);
 382         __mod_zone_page_state(zone, item, delta);
 383         local_irq_restore(flags);
 384 }
 385 EXPORT_SYMBOL(mod_zone_page_state);
 386
 387 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 388 {
 389         unsigned long flags;
 390
 391         local_irq_save(flags);
 392         __inc_zone_state(zone, item);
 393         local_irq_restore(flags);
 394 }
 395
 396 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 397 {
 398         unsigned long flags;
 399         struct zone *zone;
 400
 401         zone = page_zone(page);
 402         local_irq_save(flags);
 403         __inc_zone_state(zone, item);
 404         local_irq_restore(flags);
 405 }
 406 EXPORT_SYMBOL(inc_zone_page_state);
 407
 408 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 409 {
 410         unsigned long flags;
 411
 412         local_irq_save(flags);
 413         __dec_zone_page_state(page, item);
 414         local_irq_restore(flags);
 415 }
 416 EXPORT_SYMBOL(dec_zone_page_state);
 417 #endif
 418
 419 /*
 420  * Update the zone counters for one cpu.
 421  *
 422  * The cpu specified must be either the current cpu or a processor that
 423  * is not online. If it is the current cpu then the execution thread must
 424  * be pinned to the current cpu.
 425  *
 426  * Note that refresh_cpu_vm_stats strives to only access
 427  * node local memory. The per cpu pagesets on remote zones are placed
 428  * in the memory local to the processor using that pageset. So the
 429  * loop over all zones will access a series of cachelines local to
 430  * the processor.
 431  *
 432  * The call to zone_page_state_add updates the cachelines with the
 433  * statistics in the remote zone struct as well as the global cachelines
 434  * with the global counters. These could cause remote node cache line
 435  * bouncing and will have to be only done when necessary.
 436  */
 437 void refresh_cpu_vm_stats(int cpu)
 438 {
 439         struct zone *zone;
 440         int i;
 441         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 442
 443         for_each_populated_zone(zone) {
 444                 struct per_cpu_pageset *p;
 445
 446                 p = per_cpu_ptr(zone->pageset, cpu);
 447
 448                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 449                         if (p->vm_stat_diff[i]) {
 450                                 unsigned long flags;
 451                                 int v;
 452
 453                                 local_irq_save(flags);
 454                                 v = p->vm_stat_diff[i];
 455                                 p->vm_stat_diff[i] = 0;
 456                                 local_irq_restore(flags);
 457                                 atomic_long_add(v, &zone->vm_stat[i]);
 458                                 global_diff[i] += v;
 459 #ifdef CONFIG_NUMA
 460                                 /* 3 seconds idle till flush */
 461                                 p->expire = 3;
 462 #endif
 463                         }
 464                 cond_resched();
 465 #ifdef CONFIG_NUMA
 466                 /*
 467                  * Deal with draining the remote pageset of this
 468                  * processor
 469                  *
 470                  * Check if there are pages remaining in this pageset
 471                  * if not then there is nothing to expire.
 472                  */
 473                 if (!p->expire || !p->pcp.count)
 474                         continue;
 475
 476                 /*
 477                  * We never drain zones local to this processor.
 478                  */
 479                 if (zone_to_nid(zone) == numa_node_id()) {
 480                         p->expire = 0;
 481                         continue;
 482                 }
 483
 484                 p->expire--;
 485                 if (p->expire)
 486                         continue;
 487
 488                 if (p->pcp.count)
 489                         drain_zone_pages(zone, &p->pcp);
 490 #endif
 491         }
 492
 493         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 494                 if (global_diff[i])
 495                         atomic_long_add(global_diff[i], &vm_stat[i]);
 496 }
 497
 498 void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
 499 {
 500         int i;
 501
 502         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 503                 if (pset->vm_stat_diff[i]) {
 504                         int v = pset->vm_stat_diff[i];
 505                         pset->vm_stat_diff[i] = 0;
 506                         atomic_long_add(v, &zone->vm_stat[i]);
 507                         atomic_long_add(v, &vm_stat[i]);
 508                 }
 509 }
 510 #endif
 511
 512 #ifdef CONFIG_NUMA
 513 /*
 514  * zonelist = the list of zones passed to the allocator
 515  * z        = the zone from which the allocation occurred.
 516  *
 517  * Must be called with interrupts disabled.
 518  *
 519  * When __GFP_OTHER_NODE is set assume the node of the preferred
 520  * zone is the local node. This is useful for daemons who allocate
 521  * memory on behalf of other processes.
 522  */
 523 void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 524 {
 525         if (z->zone_pgdat == preferred_zone->zone_pgdat) {
 526                 __inc_zone_state(z, NUMA_HIT);
 527         } else {
 528                 __inc_zone_state(z, NUMA_MISS);
 529                 __inc_zone_state(preferred_zone, NUMA_FOREIGN);
 530         }
 531         if (z->node == ((flags & __GFP_OTHER_NODE) ?
 532                         preferred_zone->node : numa_node_id()))
 533                 __inc_zone_state(z, NUMA_LOCAL);
 534         else
 535                 __inc_zone_state(z, NUMA_OTHER);
 536 }
 537 #endif
 538
 539 #ifdef CONFIG_COMPACTION
 540
 541 struct contig_page_info {
 542         unsigned long free_pages;
 543         unsigned long free_blocks_total;
 544         unsigned long free_blocks_suitable;
 545 };
 546
 547 /*
 548  * Calculate the number of free pages in a zone, how many contiguous
 549  * pages are free and how many are large enough to satisfy an allocation of
 550  * the target size. Note that this function makes no attempt to estimate
 551  * how many suitable free blocks there *might* be if MOVABLE pages were
 552  * migrated. Calculating that is possible, but expensive and can be
 553  * figured out from userspace
 554  */
 555 static void fill_contig_page_info(struct zone *zone,
 556                                 unsigned int suitable_order,
 557                                 struct contig_page_info *info)
 558 {
 559         unsigned int order;
 560
 561         info->free_pages = 0;
 562         info->free_blocks_total = 0;
 563         info->free_blocks_suitable = 0;
 564
 565         for (order = 0; order < MAX_ORDER; order++) {
 566                 unsigned long blocks;
 567
 568                 /* Count number of free blocks */
 569                 blocks = zone->free_area[order].nr_free;
 570                 info->free_blocks_total += blocks;
 571
 572                 /* Count free base pages */
 573                 info->free_pages += blocks << order;
 574
 575                 /* Count the suitable free blocks */
 576                 if (order >= suitable_order)
 577                         info->free_blocks_suitable += blocks <<
 578                                                 (order - suitable_order);
 579         }
 580 }
 581
 582 /*
 583  * A fragmentation index only makes sense if an allocation of a requested
 584  * size would fail. If that is true, the fragmentation index indicates
 585  * whether external fragmentation or a lack of memory was the problem.
 586  * The value can be used to determine if page reclaim or compaction
 587  * should be used
 588  */
 589 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 590 {
 591         unsigned long requested = 1UL << order;
 592
 593         if (!info->free_blocks_total)
 594                 return 0;
 595
 596         /* Fragmentation index only makes sense when a request would fail */
 597         if (info->free_blocks_suitable)
 598                 return -1000;
 599
 600         /*
 601          * Index is between 0 and 1 so return within 3 decimal places
 602          *
 603          * 0 => allocation would fail due to lack of memory
 604          * 1 => allocation would fail due to fragmentation
 605          */
 606         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 607 }
 608
 609 /* Same as __fragmentation index but allocs contig_page_info on stack */
 610 int fragmentation_index(struct zone *zone, unsigned int order)
 611 {
 612         struct contig_page_info info;
 613
 614         fill_contig_page_info(zone, order, &info);
 615         return __fragmentation_index(order, &info);
 616 }
 617 #endif
 618
 619 #if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
 620 #include <linux/proc_fs.h>
 621 #include <linux/seq_file.h>
 622
 623 static char * const migratetype_names[MIGRATE_TYPES] = {
 624         "Unmovable",
 625         "Reclaimable",
 626         "Movable",
 627         "Reserve",
 628 #ifdef CONFIG_CMA
 629         "CMA",
 630 #endif
 631         "Isolate",
 632 };
 633
 634 static void *frag_start(struct seq_file *m, loff_t *pos)
 635 {
 636         pg_data_t *pgdat;
 637         loff_t node = *pos;
 638         for (pgdat = first_online_pgdat();
 639              pgdat && node;
 640              pgdat = next_online_pgdat(pgdat))
 641                 --node;
 642
 643         return pgdat;
 644 }
 645
 646 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 647 {
 648         pg_data_t *pgdat = (pg_data_t *)arg;
 649
 650         (*pos)++;
 651         return next_online_pgdat(pgdat);
 652 }
 653
 654 static void frag_stop(struct seq_file *m, void *arg)
 655 {
 656 }
 657
 658 /* Walk all the zones in a node and print using a callback */
 659 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 660                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 661 {
 662         struct zone *zone;
 663         struct zone *node_zones = pgdat->node_zones;
 664         unsigned long flags;
 665
 666         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 667                 if (!populated_zone(zone))
 668                         continue;
 669
 670                 spin_lock_irqsave(&zone->lock, flags);
 671                 print(m, pgdat, zone);
 672                 spin_unlock_irqrestore(&zone->lock, flags);
 673         }
 674 }
 675 #endif
 676
 677 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 678 #ifdef CONFIG_ZONE_DMA
 679 #define TEXT_FOR_DMA(xx) xx "_dma",
 680 #else
 681 #define TEXT_FOR_DMA(xx)
 682 #endif
 683
 684 #ifdef CONFIG_ZONE_DMA32
 685 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 686 #else
 687 #define TEXT_FOR_DMA32(xx)
 688 #endif
 689
 690 #ifdef CONFIG_HIGHMEM
 691 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
 692 #else
 693 #define TEXT_FOR_HIGHMEM(xx)
 694 #endif
 695
 696 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 697                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
 698
 699 const char * const vmstat_text[] = {
 700         /* Zoned VM counters */
 701         "nr_free_pages",
 702         "nr_inactive_anon",
 703         "nr_active_anon",
 704         "nr_inactive_file",
 705         "nr_active_file",
 706         "nr_unevictable",
 707         "nr_mlock",
 708         "nr_anon_pages",
 709         "nr_mapped",
 710         "nr_file_pages",
 711         "nr_dirty",
 712         "nr_writeback",
 713         "nr_slab_reclaimable",
 714         "nr_slab_unreclaimable",
 715         "nr_page_table_pages",
 716         "nr_kernel_stack",
 717         "nr_unstable",
 718         "nr_bounce",
 719         "nr_vmscan_write",
 720         "nr_vmscan_immediate_reclaim",
 721         "nr_writeback_temp",
 722         "nr_isolated_anon",
 723         "nr_isolated_file",
 724         "nr_shmem",
 725         "nr_dirtied",
 726         "nr_written",
 727
 728 #ifdef CONFIG_NUMA
 729         "numa_hit",
 730         "numa_miss",
 731         "numa_foreign",
 732         "numa_interleave",
 733         "numa_local",
 734         "numa_other",
 735 #endif
 736         "nr_anon_transparent_hugepages",
 737         "nr_free_cma",
 738         "nr_dirty_threshold",
 739         "nr_dirty_background_threshold",
 740
 741 #ifdef CONFIG_VM_EVENT_COUNTERS
 742         "pgpgin",
 743         "pgpgout",
 744         "pswpin",
 745         "pswpout",
 746
 747         TEXTS_FOR_ZONES("pgalloc")
 748
 749         "pgfree",
 750         "pgactivate",
 751         "pgdeactivate",
 752
 753         "pgfault",
 754         "pgmajfault",
 755
 756         TEXTS_FOR_ZONES("pgrefill")
 757         TEXTS_FOR_ZONES("pgsteal_kswapd")
 758         TEXTS_FOR_ZONES("pgsteal_direct")
 759         TEXTS_FOR_ZONES("pgscan_kswapd")
 760         TEXTS_FOR_ZONES("pgscan_direct")
 761         "pgscan_direct_throttle",
 762
 763 #ifdef CONFIG_NUMA
 764         "zone_reclaim_failed",
 765 #endif
 766         "pginodesteal",
 767         "slabs_scanned",
 768         "kswapd_inodesteal",
 769         "kswapd_low_wmark_hit_quickly",
 770         "kswapd_high_wmark_hit_quickly",
 771         "kswapd_skip_congestion_wait",
 772         "pageoutrun",
 773         "allocstall",
 774
 775         "pgrotated",
 776
 777 #ifdef CONFIG_COMPACTION
 778         "compact_blocks_moved",
 779         "compact_pages_moved",
 780         "compact_pagemigrate_failed",
 781         "compact_stall",
 782         "compact_fail",
 783         "compact_success",
 784 #endif
 785
 786 #ifdef CONFIG_HUGETLB_PAGE
 787         "htlb_buddy_alloc_success",
 788         "htlb_buddy_alloc_fail",
 789 #endif
 790         "unevictable_pgs_culled",
 791         "unevictable_pgs_scanned",
 792         "unevictable_pgs_rescued",
 793         "unevictable_pgs_mlocked",
 794         "unevictable_pgs_munlocked",
 795         "unevictable_pgs_cleared",
 796         "unevictable_pgs_stranded",
 797         "unevictable_pgs_mlockfreed",   /* no longer useful: always zero */
 798
 799 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 800         "thp_fault_alloc",
 801         "thp_fault_fallback",
 802         "thp_collapse_alloc",
 803         "thp_collapse_alloc_failed",
 804         "thp_split",
 805 #endif
 806
 807 #endif /* CONFIG_VM_EVENTS_COUNTERS */
 808 };
 809 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 810
 811
 812 #ifdef CONFIG_PROC_FS
 813 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 814                                                 struct zone *zone)
 815 {
 816         int order;
 817
 818         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 819         for (order = 0; order < MAX_ORDER; ++order)
 820                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 821         seq_putc(m, '\n');
 822 }
 823
 824 /*
 825  * This walks the free areas for each zone.
 826  */
 827 static int frag_show(struct seq_file *m, void *arg)
 828 {
 829         pg_data_t *pgdat = (pg_data_t *)arg;
 830         walk_zones_in_node(m, pgdat, frag_show_print);
 831         return 0;
 832 }
 833
 834 static void pagetypeinfo_showfree_print(struct seq_file *m,
 835                                         pg_data_t *pgdat, struct zone *zone)
 836 {
 837         int order, mtype;
 838
 839         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 840                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
 841                                         pgdat->node_id,
 842                                         zone->name,
 843                                         migratetype_names[mtype]);
 844                 for (order = 0; order < MAX_ORDER; ++order) {
 845                         unsigned long freecount = 0;
 846                         struct free_area *area;
 847                         struct list_head *curr;
 848
 849                         area = &(zone->free_area[order]);
 850
 851                         list_for_each(curr, &area->free_list[mtype])
 852                                 freecount++;
 853                         seq_printf(m, "%6lu ", freecount);
 854                 }
 855                 seq_putc(m, '\n');
 856         }
 857 }
 858
 859 /* Print out the free pages at each order for each migatetype */
 860 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 861 {
 862         int order;
 863         pg_data_t *pgdat = (pg_data_t *)arg;
 864
 865         /* Print header */
 866         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 867         for (order = 0; order < MAX_ORDER; ++order)
 868                 seq_printf(m, "%6d ", order);
 869         seq_putc(m, '\n');
 870
 871         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 872
 873         return 0;
 874 }
 875
 876 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 877                                         pg_data_t *pgdat, struct zone *zone)
 878 {
 879         int mtype;
 880         unsigned long pfn;
 881         unsigned long start_pfn = zone->zone_start_pfn;
 882         unsigned long end_pfn = start_pfn + zone->spanned_pages;
 883         unsigned long count[MIGRATE_TYPES] = { 0, };
 884
 885         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 886                 struct page *page;
 887
 888                 if (!pfn_valid(pfn))
 889                         continue;
 890
 891                 page = pfn_to_page(pfn);
 892
 893                 /* Watch for unexpected holes punched in the memmap */
 894                 if (!memmap_valid_within(pfn, page, zone))
 895                         continue;
 896
 897                 mtype = get_pageblock_migratetype(page);
 898
 899                 if (mtype < MIGRATE_TYPES)
 900                         count[mtype]++;
 901         }
 902
 903         /* Print counts */
 904         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 905         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 906                 seq_printf(m, "%12lu ", count[mtype]);
 907         seq_putc(m, '\n');
 908 }
 909
 910 /* Print out the free pages at each order for each migratetype */
 911 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 912 {
 913         int mtype;
 914         pg_data_t *pgdat = (pg_data_t *)arg;
 915
 916         seq_printf(m, "\n%-23s", "Number of blocks type ");
 917         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 918                 seq_printf(m, "%12s ", migratetype_names[mtype]);
 919         seq_putc(m, '\n');
 920         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 921
 922         return 0;
 923 }
 924
 925 /*
 926  * This prints out statistics in relation to grouping pages by mobility.
 927  * It is expensive to collect so do not constantly read the file.
 928  */
 929 static int pagetypeinfo_show(struct seq_file *m, void *arg)
 930 {
 931         pg_data_t *pgdat = (pg_data_t *)arg;
 932
 933         /* check memoryless node */
 934         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
 935                 return 0;
 936
 937         seq_printf(m, "Page block order: %d\n", pageblock_order);
 938         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 939         seq_putc(m, '\n');
 940         pagetypeinfo_showfree(m, pgdat);
 941         pagetypeinfo_showblockcount(m, pgdat);
 942
 943         return 0;
 944 }
 945
 946 static const struct seq_operations fragmentation_op = {
 947         .start  = frag_start,
 948         .next   = frag_next,
 949         .stop   = frag_stop,
 950         .show   = frag_show,
 951 };
 952
 953 static int fragmentation_open(struct inode *inode, struct file *file)
 954 {
 955         return seq_open(file, &fragmentation_op);
 956 }
 957
 958 static const struct file_operations fragmentation_file_operations = {
 959         .open           = fragmentation_open,
 960         .read           = seq_read,
 961         .llseek         = seq_lseek,
 962         .release        = seq_release,
 963 };
 964
 965 static const struct seq_operations pagetypeinfo_op = {
 966         .start  = frag_start,
 967         .next   = frag_next,
 968         .stop   = frag_stop,
 969         .show   = pagetypeinfo_show,
 970 };
 971
 972 static int pagetypeinfo_open(struct inode *inode, struct file *file)
 973 {
 974         return seq_open(file, &pagetypeinfo_op);
 975 }
 976
 977 static const struct file_operations pagetypeinfo_file_ops = {
 978         .open           = pagetypeinfo_open,
 979         .read           = seq_read,
 980         .llseek         = seq_lseek,
 981         .release        = seq_release,
 982 };
 983
 984 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 985                                                         struct zone *zone)
 986 {
 987         int i;
 988         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
 989         seq_printf(m,
 990                    "\n  pages free     %lu"
 991                    "\n        min      %lu"
 992                    "\n        low      %lu"
 993                    "\n        high     %lu"
 994                    "\n        scanned  %lu"
 995                    "\n        spanned  %lu"
 996                    "\n        present  %lu",
 997                    zone_page_state(zone, NR_FREE_PAGES),
 998                    min_wmark_pages(zone),
 999                    low_wmark_pages(zone),
1000                    high_wmark_pages(zone),
1001                    zone->pages_scanned,
1002                    zone->spanned_pages,
1003                    zone->present_pages);
1004
1005         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1006                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
1007                                 zone_page_state(zone, i));
1008
1009         seq_printf(m,
1010                    "\n        protection: (%lu",
1011                    zone->lowmem_reserve[0]);
1012         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1013                 seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
1014         seq_printf(m,
1015                    ")"
1016                    "\n  pagesets");
1017         for_each_online_cpu(i) {
1018                 struct per_cpu_pageset *pageset;
1019
1020                 pageset = per_cpu_ptr(zone->pageset, i);
1021                 seq_printf(m,
1022                            "\n    cpu: %i"
1023                            "\n              count: %i"
1024                            "\n              high:  %i"
1025                            "\n              batch: %i",
1026                            i,
1027                            pageset->pcp.count,
1028                            pageset->pcp.high,
1029                            pageset->pcp.batch);
1030 #ifdef CONFIG_SMP
1031                 seq_printf(m, "\n  vm stats threshold: %d",
1032                                 pageset->stat_threshold);
1033 #endif
1034         }
1035         seq_printf(m,
1036                    "\n  all_unreclaimable: %u"
1037                    "\n  start_pfn:         %lu"
1038                    "\n  inactive_ratio:    %u",
1039                    zone->all_unreclaimable,
1040                    zone->zone_start_pfn,
1041                    zone->inactive_ratio);
1042         seq_putc(m, '\n');
1043 }
1044
1045 /*
1046  * Output information about zones in @pgdat.
1047  */
1048 static int zoneinfo_show(struct seq_file *m, void *arg)
1049 {
1050         pg_data_t *pgdat = (pg_data_t *)arg;
1051         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1052         return 0;
1053 }
1054
1055 static const struct seq_operations zoneinfo_op = {
1056         .start  = frag_start, /* iterate over all zones. The same as in
1057                                * fragmentation. */
1058         .next   = frag_next,
1059         .stop   = frag_stop,
1060         .show   = zoneinfo_show,
1061 };
1062
1063 static int zoneinfo_open(struct inode *inode, struct file *file)
1064 {
1065         return seq_open(file, &zoneinfo_op);
1066 }
1067
1068 static const struct file_operations proc_zoneinfo_file_operations = {
1069         .open           = zoneinfo_open,
1070         .read           = seq_read,
1071         .llseek         = seq_lseek,
1072         .release        = seq_release,
1073 };
1074
1075 enum writeback_stat_item {
1076         NR_DIRTY_THRESHOLD,
1077         NR_DIRTY_BG_THRESHOLD,
1078         NR_VM_WRITEBACK_STAT_ITEMS,
1079 };
1080
1081 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1082 {
1083         unsigned long *v;
1084         int i, stat_items_size;
1085
1086         if (*pos >= ARRAY_SIZE(vmstat_text))
1087                 return NULL;
1088         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1089                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1090
1091 #ifdef CONFIG_VM_EVENT_COUNTERS
1092         stat_items_size += sizeof(struct vm_event_state);
1093 #endif
1094
1095         v = kmalloc(stat_items_size, GFP_KERNEL);
1096         m->private = v;
1097         if (!v)
1098                 return ERR_PTR(-ENOMEM);
1099         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1100                 v[i] = global_page_state(i);
1101         v += NR_VM_ZONE_STAT_ITEMS;
1102
1103         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1104                             v + NR_DIRTY_THRESHOLD);
1105         v += NR_VM_WRITEBACK_STAT_ITEMS;
1106
1107 #ifdef CONFIG_VM_EVENT_COUNTERS
1108         all_vm_events(v);
1109         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1110         v[PGPGOUT] /= 2;
1111 #endif
1112         return (unsigned long *)m->private + *pos;
1113 }
1114
1115 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1116 {
1117         (*pos)++;
1118         if (*pos >= ARRAY_SIZE(vmstat_text))
1119                 return NULL;
1120         return (unsigned long *)m->private + *pos;
1121 }
1122
1123 static int vmstat_show(struct seq_file *m, void *arg)
1124 {
1125         unsigned long *l = arg;
1126         unsigned long off = l - (unsigned long *)m->private;
1127
1128         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1129         return 0;
1130 }
1131
1132 static void vmstat_stop(struct seq_file *m, void *arg)
1133 {
1134         kfree(m->private);
1135         m->private = NULL;
1136 }
1137
1138 static const struct seq_operations vmstat_op = {
1139         .start  = vmstat_start,
1140         .next   = vmstat_next,
1141         .stop   = vmstat_stop,
1142         .show   = vmstat_show,
1143 };
1144
1145 static int vmstat_open(struct inode *inode, struct file *file)
1146 {
1147         return seq_open(file, &vmstat_op);
1148 }
1149
1150 static const struct file_operations proc_vmstat_file_operations = {
1151         .open           = vmstat_open,
1152         .read           = seq_read,
1153         .llseek         = seq_lseek,
1154         .release        = seq_release,
1155 };
1156 #endif /* CONFIG_PROC_FS */
1157
1158 #ifdef CONFIG_SMP
1159 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1160 int sysctl_stat_interval __read_mostly = HZ;
1161
1162 static void vmstat_update(struct work_struct *w)
1163 {
1164         refresh_cpu_vm_stats(smp_processor_id());
1165         schedule_delayed_work(&__get_cpu_var(vmstat_work),
1166                 round_jiffies_relative(sysctl_stat_interval));
1167 }
1168
1169 static void __cpuinit start_cpu_timer(int cpu)
1170 {
1171         struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1172
1173         INIT_DEFERRABLE_WORK(work, vmstat_update);
1174         schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1175 }
1176
1177 /*
1178  * Use the cpu notifier to insure that the thresholds are recalculated
1179  * when necessary.
1180  */
1181 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1182                 unsigned long action,
1183                 void *hcpu)
1184 {
1185         long cpu = (long)hcpu;
1186
1187         switch (action) {
1188         case CPU_ONLINE:
1189         case CPU_ONLINE_FROZEN:
1190                 refresh_zone_stat_thresholds();
1191                 start_cpu_timer(cpu);
1192                 node_set_state(cpu_to_node(cpu), N_CPU);
1193                 break;
1194         case CPU_DOWN_PREPARE:
1195         case CPU_DOWN_PREPARE_FROZEN:
1196                 cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1197                 per_cpu(vmstat_work, cpu).work.func = NULL;
1198                 break;
1199         case CPU_DOWN_FAILED:
1200         case CPU_DOWN_FAILED_FROZEN:
1201                 start_cpu_timer(cpu);
1202                 break;
1203         case CPU_DEAD:
1204         case CPU_DEAD_FROZEN:
1205                 refresh_zone_stat_thresholds();
1206                 break;
1207         default:
1208                 break;
1209         }
1210         return NOTIFY_OK;
1211 }
1212
1213 static struct notifier_block __cpuinitdata vmstat_notifier =
1214         { &vmstat_cpuup_callback, NULL, 0 };
1215 #endif
1216
1217 static int __init setup_vmstat(void)
1218 {
1219 #ifdef CONFIG_SMP
1220         int cpu;
1221
1222         register_cpu_notifier(&vmstat_notifier);
1223
1224         for_each_online_cpu(cpu)
1225                 start_cpu_timer(cpu);
1226 #endif
1227 #ifdef CONFIG_PROC_FS
1228         proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1229         proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1230         proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1231         proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1232 #endif
1233         return 0;
1234 }
1235 module_init(setup_vmstat)
1236
1237 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1238 #include <linux/debugfs.h>
1239
1240
1241 /*
1242  * Return an index indicating how much of the available free memory is
1243  * unusable for an allocation of the requested size.
1244  */
1245 static int unusable_free_index(unsigned int order,
1246                                 struct contig_page_info *info)
1247 {
1248         /* No free memory is interpreted as all free memory is unusable */
1249         if (info->free_pages == 0)
1250                 return 1000;
1251
1252         /*
1253          * Index should be a value between 0 and 1. Return a value to 3
1254          * decimal places.
1255          *
1256          * 0 => no fragmentation
1257          * 1 => high fragmentation
1258          */
1259         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1260
1261 }
1262
1263 static void unusable_show_print(struct seq_file *m,
1264                                         pg_data_t *pgdat, struct zone *zone)
1265 {
1266         unsigned int order;
1267         int index;
1268         struct contig_page_info info;
1269
1270         seq_printf(m, "Node %d, zone %8s ",
1271                                 pgdat->node_id,
1272                                 zone->name);
1273         for (order = 0; order < MAX_ORDER; ++order) {
1274                 fill_contig_page_info(zone, order, &info);
1275                 index = unusable_free_index(order, &info);
1276                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1277         }
1278
1279         seq_putc(m, '\n');
1280 }
1281
1282 /*
1283  * Display unusable free space index
1284  *
1285  * The unusable free space index measures how much of the available free
1286  * memory cannot be used to satisfy an allocation of a given size and is a
1287  * value between 0 and 1. The higher the value, the more of free memory is
1288  * unusable and by implication, the worse the external fragmentation is. This
1289  * can be expressed as a percentage by multiplying by 100.
1290  */
1291 static int unusable_show(struct seq_file *m, void *arg)
1292 {
1293         pg_data_t *pgdat = (pg_data_t *)arg;
1294
1295         /* check memoryless node */
1296         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
1297                 return 0;
1298
1299         walk_zones_in_node(m, pgdat, unusable_show_print);
1300
1301         return 0;
1302 }
1303
1304 static const struct seq_operations unusable_op = {
1305         .start  = frag_start,
1306         .next   = frag_next,
1307         .stop   = frag_stop,
1308         .show   = unusable_show,
1309 };
1310
1311 static int unusable_open(struct inode *inode, struct file *file)
1312 {
1313         return seq_open(file, &unusable_op);
1314 }
1315
1316 static const struct file_operations unusable_file_ops = {
1317         .open           = unusable_open,
1318         .read           = seq_read,
1319         .llseek         = seq_lseek,
1320         .release        = seq_release,
1321 };
1322
1323 static void extfrag_show_print(struct seq_file *m,
1324                                         pg_data_t *pgdat, struct zone *zone)
1325 {
1326         unsigned int order;
1327         int index;
1328
1329         /* Alloc on stack as interrupts are disabled for zone walk */
1330         struct contig_page_info info;
1331
1332         seq_printf(m, "Node %d, zone %8s ",
1333                                 pgdat->node_id,
1334                                 zone->name);
1335         for (order = 0; order < MAX_ORDER; ++order) {
1336                 fill_contig_page_info(zone, order, &info);
1337                 index = __fragmentation_index(order, &info);
1338                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1339         }
1340
1341         seq_putc(m, '\n');
1342 }
1343
1344 /*
1345  * Display fragmentation index for orders that allocations would fail for
1346  */
1347 static int extfrag_show(struct seq_file *m, void *arg)
1348 {
1349         pg_data_t *pgdat = (pg_data_t *)arg;
1350
1351         walk_zones_in_node(m, pgdat, extfrag_show_print);
1352
1353         return 0;
1354 }
1355
1356 static const struct seq_operations extfrag_op = {
1357         .start  = frag_start,
1358         .next   = frag_next,
1359         .stop   = frag_stop,
1360         .show   = extfrag_show,
1361 };
1362
1363 static int extfrag_open(struct inode *inode, struct file *file)
1364 {
1365         return seq_open(file, &extfrag_op);
1366 }
1367
1368 static const struct file_operations extfrag_file_ops = {
1369         .open           = extfrag_open,
1370         .read           = seq_read,
1371         .llseek         = seq_lseek,
1372         .release        = seq_release,
1373 };
1374
1375 static int __init extfrag_debug_init(void)
1376 {
1377         struct dentry *extfrag_debug_root;
1378
1379         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1380         if (!extfrag_debug_root)
1381                 return -ENOMEM;
1382
1383         if (!debugfs_create_file("unusable_index", 0444,
1384                         extfrag_debug_root, NULL, &unusable_file_ops))
1385                 goto fail;
1386
1387         if (!debugfs_create_file("extfrag_index", 0444,
1388                         extfrag_debug_root, NULL, &extfrag_file_ops))
1389                 goto fail;
1390
1391         return 0;
1392 fail:
1393         debugfs_remove_recursive(extfrag_debug_root);
1394         return -ENOMEM;
1395 }
1396
1397 module_init(extfrag_debug_init);
1398 #endif